import java.math.BigInteger;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        System.out.println(func(n));
    }
    public static BigInteger func(int n){
        BigInteger result=BigInteger.ONE;
        for(int i=1;i<=n;i++){
            result=result.multiply(BigInteger.valueOf(i));
        }
        return result;
    }
}